Influence of the substitution of Y2O3 for CeO2 on the mechanical and microstructural properties of silicon nitride
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Data
2005-09-01
Autores
Souza, J. V. C. de [UNESP]
Kelly, C. A.
Moreira, M. R. V.
Ribeiro, M. V.
Santos, C. dos
Silva, O. M. M.
Lanna, M. A.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Associação Brasileira de Cerâmica
Resumo
Este trabalho foi proposto com objetivo de analisar a possibilidade da substituição de Y2O3 por CeO2 sinterização via fase líquida de nitreto de silício (Si3N4), visando obter um material com boas propriedades físicas, mecânicas e microestruturais, além da redução de custos de produção desta cerâmica. Para o desenvolvimento deste trabalho foram preparadas duas misturas de pós, variando-se as proporções entre alfa-Si3N4, Al2O3, AlN, Y2O3 e CeO2. As misturas de pós foram homogeneizadas em etanol, secas em evaporador rotativo e estufa, respectivamente. em seguida, prensadas uniaxialmente (100 MPa) e isostaticamente a frio(300 MPa). As amostras foram sinterizadas à 1850 ºC durante 1 h, em forno com elemento resistivo de grafite sob atmosfera de nitrogênio. Após sinterização, as amostras apresentaram densidades relativas superiores a 97% do valor teórico. A tenacidade à fratura e a dureza foram superiores a 5,28 MPa.m½ e 17,12 GPa, respectivamente. As análises de fases por difração de raios X e microscopia eletrônica de varredura mostraram a presença das fases alfa-SiAlON e beta-Si3N4.
This work investigated the substitution of Y2O3 for CeO2 in liquid-phase sintered silicon nitride ceramics. Cost reduction as well as good physical, mechanical and microstructural properties are the main objectives of the present study. Two powder mixtures were prepared, varying the contents of alpha-Si3N4, Al2O3, AlN, Y2O3 and CeO2. The mixtures were homogenized in ethanol, dried in a rotating evaporator and kiln, respectively, and then uniaxially (100 MPa) and cold isostatically pressed (300 MPa). The samples were sintered at 1850ºC for 1 h in a graphite resistive furnace under nitrogen atmosphere. After sintering the density of the samples was higher than 97% of the theoretical value. The fracture toughness and hardness were higher than 5.28 MPa.m½ and 17.12 GPa, respectively. Phase analysis by X-ray diffraction and scanning electron microscopy revealed the presence of alpha-SiAlON and beta-Si3N4.
This work investigated the substitution of Y2O3 for CeO2 in liquid-phase sintered silicon nitride ceramics. Cost reduction as well as good physical, mechanical and microstructural properties are the main objectives of the present study. Two powder mixtures were prepared, varying the contents of alpha-Si3N4, Al2O3, AlN, Y2O3 and CeO2. The mixtures were homogenized in ethanol, dried in a rotating evaporator and kiln, respectively, and then uniaxially (100 MPa) and cold isostatically pressed (300 MPa). The samples were sintered at 1850ºC for 1 h in a graphite resistive furnace under nitrogen atmosphere. After sintering the density of the samples was higher than 97% of the theoretical value. The fracture toughness and hardness were higher than 5.28 MPa.m½ and 17.12 GPa, respectively. Phase analysis by X-ray diffraction and scanning electron microscopy revealed the presence of alpha-SiAlON and beta-Si3N4.
Descrição
Palavras-chave
Si3N4, fase líquida, Y2O3, CeO2, tenacidade à fratura, dureza, Si3N4, liquid-phase, Y2O3, CeO2, fracture toughness, hardness
Como citar
Cerâmica. Associação Brasileira de Cerâmica, v. 51, n. 319, p. 285-288, 2005.